Vernor Vinge has a name for them: localizers

[OT from cottage renovations]

Downstream from the Supply Chain is: the Removal Chain, visualized here by MIT. 

But even more interesting was this teaser: "TrashTrack uses hundreds of small, smart, location aware tags: a first step towards the deployment of smart-dust - networks of tiny locatable and addressable microeletromechanical systems.  These tags are attached to different types of trash so that these items can be followed through the city’s waste management system [...]"

(from Ateneo Naider)